Image information is an important class of information that can be obtained by humans, and an optical lens is almost the only entry point for obtaining the image information. With the progress in science and technology, quality and information quantity of an image obtained by the population are continuously increasing. The quality of the image is mainly achieved by increasing the pixel sampling density of a photosensitive element. Therefore, an increase of an aperture in a system and an increase of transfer function of each field of view of the system are needed to meet the above requirement. The information quantity of the image obtained by the optical system may be represented by an optical invariant of the system, and the optical invariant of the system increases linearly with the field of view of the optical system.
Therefore, in order to increase the information quantity of the obtained image, a main approach is to increase the field of view of the optical system. At present, with the development of mobile phone lenses, consumers have higher and higher demands for selfies. Accordingly, it is quite necessary to develop a wide-angle lens assembly that has a large field of view and high resolution and is suitable for taking the selfie. Due to the height limit of the mobile phone lens, the length of the optical system is compressed as much as possible while taking the large field of view, the high resolution and high yield rate into account.